Electric-motor controller.



APPLICATION FILED SEPT.18,1913.

Patented. July 21, 1914 Ll/l ATTORNEY UNITED snares earns orrion.

HOMER E. FROST, OF CLEVELAND, OHIO, ASSIGNOR TO THE ELECTRIC CONTROLLER AND MANUFACTURING GOMPA'NY, OF CLEVELAND, OHIO,

A CORPORATION OF OHIO.

ELECTRIC-MOTOR CONTROLLER.

Specification of Letters Patent.

Patented July 2t, 1914.

Application filed September 13, 1913. Serial No. 785,654.

To all whom 1'1; may concern:

Be it known that I, citizen of the United States, residing at Cleveland, in the county of Cuyahoga and State of Ohio, have invented new and useful Improvements in Electric-Motor Controllore, of which the following is a specification.

My invention relates to an electric motor controller in which the motor circuit is controlled at the contacts of a manually-open ated switch and at the contacts of a. series of magnetically-operated switches.

More particularly, it relates to such a controller in which. the operating windings of the switches are arranged to be connected in the motor circuit.

One of the objects of my invention is to enable the operator to maintain at will the maximum resistance in the motor circuit.

A further object is to prevent the closure of the first magnetically-operated switch untilthe first section of the starting resistance has been cutout at the contacts of the operators switch.

Other objects and advantages of my invention will be readily understood as hereinafter described.

The accompanying drawing is a diagrammatic reprcsentatitm of an electric controller embodying my invention.

teller-ring to the drawing the switch for controlling the motor is indicated at M.

which has stationary and movable contacts including connections for reversing the motor.

The motor to be controlled is indicated with the armature A and the series field i The starting resistances are shown at It, I", R and it.

The 1nagnoticallvoporatcd switches for controlling the resistance are indicated at switches 5, S and S these switches having operating windings C, C and Cf arranged to be connected in the motor circuit. I prefer to use for these switches the type of switch disclosed. in llastwoods Patent.

No. l,0-'l(),'2)2 which has the peculiar charactcristic of remaining in the open position when the current in, its operating winding is above a predetermined value, and operates to close its contacts when the current is re duccd.

The switch 9 is providedwitha winding 3 connected across the resistance R and,

l l i l l l 1;

therefore, is energized by the current fiowing through the resistance R. The winding B is wound so as to oppose the magnetism produced by the winding C and thereby prevents the operation of the switch S as long as the current flows through the rcsist' ance it. The'winding G is connected in series with the resistance B so that as the current rises and falls in resistance B itwill vary to the same extent in both of the windings G and. YB, thus preventing the op eration of the switch S as long as the resistance it is in circuit.

\Vhen the operator moves the switch M to position 1, the motor circuit is as follows:

i From the positive through the field winding F, the contact finger 8, the controller contacts to the contact finger 7, the motor arnin ture A to the contact finger 9, the controllc: contacts to the contact finger 10, the resistances It and R, the winding C, and the resistances R and R to the negative. The winding B is energized to oppose the winding C" in proportion to the current flowing through the resistance R. The switch S will, therefore, remain open as long 'as' the operators switch remains in p0- sition. 1. The maximum resistance will be retained in the motor circuit and the motor.

will operate at its slowest speed.

When the operator moves the switch M to position 2, the resistance R is cut out and the winding 13 of the switch S is deenen gizod, the resistance It being short-circuited by the contact fingers 9 and 12 throngh the contacts of the controller. If the current in. the motor circuit-exceeds a certain value, the switch i" will remain open; and when it is diminished oclow this value, the switch S closes but does not cut out any of the starting resistance. l i hen the operator moves the snitch. M to position 3 the lower connection of the winding of the switch S is conncctcd through the contact finger 13 to the contact fingers 9 and 10 and the motor cir-- cult then goes from the contact finger 13 through the winding C, the contacts of the switch S. the winding C. and the resist-- anccs l2? and R to the negative. The resistance it is cut out causing the motor to further increase its speed. If the motor current exce ds the value at which the switch S is adjusted to operate. it will re .iin open until, the motor current is diminishcci. whereupon the switch S closes its contacts, cuts out the resistance R energizes the winding C and deenergizes the winding C. The switch S thereupon drops open and the switch S remains open, due to the increased current, until it is diminished to the value to which the switch S is adjusted to operate, whereupon the switch S closes its contacts and cuts out the resistance R All of the starting resistance is now re moved from the motor circuit, there remaining' in the circuit only the windings and the contacts of the switches S and S The motor will accordingly operate at its normal speed. A

When the operators switch is moved back to position 2, the circuit through the wind ings and the contacts ofthe switches S and S will be openedand the resistances R, R and R will be inserted in the motor circuit causing the motor to decrease its speed. The switch S will close its contacts since its winding C is included in the motor circuit at this time, but the switch S cannot cause any of the starting resistance to be shortcircuited unless the operators switch is again moved to position 3.

I W en the operators switch is moved to position 1, the resistance R will be inserted in the motor circuit causing-a further reduction in the speed of the motor and the winding B will be energized causin the switch S to open. To stop the motort eoperators switch is moved to the central position as shown in the drawings, thereby opening the motor circuit. 1

When all the resistance is in the motor circuit, the switch S" remains open regardless of the value of current flowing in the motor circuit. When the resistance R is short-circuited by the movement of the operators switch, the switch S will remain open Gilly as long as the motor current exceeds a predetermined value. A further removal of the starting resistance cannot take place until the operators switch has been moved 0 position 3 whereupon the switches S and S roceed to automatically'cut out-the remainder of the starting resistance. Connections are so made with the contacts and windings of the switches S and S that, when the windings are deenergized, practically no current flows through the switch contacts. Therefore, the switches open at a time when little or no current flows through their contacts, thus preventing any serious arcing at the switch contacts. This is an advantage, because it is not necessary to provide blow-out magnets and the necessary details to extinguish arcs at the contacts of the magnetically-operated switches.

l When the operators switch M is moved to positions 4, 5 and 6, the operation will be the same as that described forthe positions. 1, 2 and3 except that the current through the motor' armature will be reversed causing mea er the motor to run in the opposite direction. In reversing the motor all the resistance can be retained in the motor circuit, if the controller is moved. to position 1 or 1.. It will be automatically removed by the closure of the switches S", S and S in accordance with the current flowing through the motor circuit when the controller is moved to position 3 or i it will be obvious to those skilled in the art that numerous changes can be made in the apparatus without departing from the spirit of my invention.

I claim 1. In a current-varying controller, a controlled circuit, resistance therefor, a series of switches for controlling the resistances, operating windings therefor energized by current in the controlled circuit, an operators switch comprising contacts for connecting the resistances and the winding of the first switch in the controlled circuit, and 11 cans for preventing the operation of the said switch when all the resistances are in circuit.

2. In. a current-varying controller, a controlled circuit, resistances for the circuit, a series of switches for controlling the resistances, operating windings therefor onergized by current in the controlled circuit, means connected to the resistance for pre venting the operation of the first switch of the series and an operators switch comprising contacts for connecting the resistances and the operating winding of the first switch in the controlled circuit, and for cutting out a portion of the resistance, thereby deenen.

gizing the said preventing means.

3. In a current-varying controller, a controlled circuit, rcsistances therefor, a series of switches l or controlling the resistances, operating windings therefor energized by current in the controlled circuit, a preventive winding for the first switch of the series, and an ope *ators switch comprising contacts for connecting the resistance and the operat ing winding of the first switch of the series in the controlled circuit, and 'for connecting the winding of the second switch in the controlled circuit.

4t. In a motor-control system, an electric motor, a circuit therefor, resistance in the circuit, a series of switches therefor, operating windings for the switches energized by current through the motor, means for connecting the resistance and the winding of the first switch in the motor circuit, means for preventing the closure of the'first switch when all the resistance is in circuit, and means for cutting out at will a portion of the resistance, thereby permitting the said first switch to close.

I 5. In a motorcontrol system, an electric motor, a circuit therefor, resistance in the circuit, operating windings therefor enerized by current through the niotor, means or connecting the resistance and the winding of the first switch of the series in the motor circuit, means for preventing the closure of the first switch when 'ell of the resistance is in the circuit, means for cutting out at will a portion of the resistance there by permitting the said first switch to close, and means for connecting the operating winding of the second switch in the motor circuit at the will of the operator.

6. In a current-varyingcontroller, a controlled circuit, resistances therefor, a series of switches for controlling the resistances, operating windings there or energized by current in the controlled circuit, an: operetors switch comprising contacts for c0nnecting the resistances and the winding of the first switch in the controlled circuitand a winding 0n the first switch energized first switch ofithe series in the controlled circuit, and a winding connected to a portion of the resistance for neutralizing the operating winding of the said first switch.

Signed at Cleveland, Ohio, this 11th day 35 of September, 1913.

HOMER E. FROST.

Witnessesz' J. H. HALL, H. M.,DIEMER. 

